Solid polyurethanes dissolved in solvents have many applications. For example, such polyurethane solutions are used in the manufacture of films, coatings as on fabric, metal and the like, and as adhesives. Unfortunately, in many of these polyurethane solutions the polyurethane begins to degrade in a relatively short time after preparation in the strongly polar solvents often required. Degradation of polyesterurethanes in solutions of ##EQU1## wherein the R's are hydrogen or alkyl groups is particularly bad. Therefore, it is desirable to be able to provide stabilized polyurethane solutions which have good storage life even under relatively high temperature conditions.